The effects of stocking rate on liveweight gain of dorper wethers

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Abstract

An experiment on the effects of stocking rate on
liveweight gain of Dorper wethers was conducted at Kabete)
in Kenya from 23rd February to 13th July, 1981. The
wethers were continuously grazed on natural pasture
predominantly composed of Kikuyu grass (Pennisetum
clandestinum).
The experimental design was completely randomized.
Each plot was set stocked with 3 wethers and there were
4 replicates. There were 3 sizes of plots, approximately
0.087, 0.0650 and 0.0433 hectares, corresponding to
stocking rates of 34.6, 51.8 and 69.1 sheep per hectare.
Results showed that the overall weight gain per head
was 7.15, 5.54 and 3.8 kg at the low, medium and high
stocking rates respectively. In the dry period (5weeks),
the wethers lost a mean weight of 0.54 kg per head at the
high and medium stocking rates. However, the wethers at
the low stocking rate gained a mean weight of 0.54 kg per
head. In the wet period (15 weeks), the wethers gained
a mean weight of 6.67, 6.10 and 4.33 kg per head at the
low medium and high stocking rates respectively. The
differences in weight.changes between the different
stocking rates for each period were only significantly
different in the overall period, (P <0.05). An evaluation
of the finishing stage showed that 50, 25 and 8% of the
sheep at the low, medium and high stocking rates
respectivel~ were ready for slaughter at the end of the
experiment.
The overall mean weight gain per hectare was
248.69, 288.14 and 262.00 kg at the low, medium and high
stocking rates respectively. In the dry period, there
was mean ~eight loss of 28.06 and 37.43 kg per hectare
at the medium and high stocking rates respectively. However,
there was mean weight gain of 18.75 kg at the low stocking
rate. In the wet period, there was mean weight gain of
229.95, 319.84 and 299.43 kg per hectare at the low,
medium and high stocking rates respectively. However,
there were no significant differences in weight changes
between stocking rates for any of the periods (P> 0.05).
There was an increased emergence of herbs and forbs
at the high stocking rate in the wet period. Changes in
foliage cover showed that Kikuyu grass was tolerant to
heavy grazing but there were signs of overgrazing at the
high stocking rate.
It was concluded that the medium stocking rate could
be suitable but with caution because it was unable to finish
off 80% of the sheep. Continuous rainfall was required if
overgrazing had to be averted at the high stocking rate.